Dishwasher



Aug. 14, 1962 J. w. JACOBS DISHWASHER Filed Aug. 51, 1959 m m m V .M

Rinsin 7 s/ve Line Switch g- 3 INVENTOR.

James W. Jacobs BY H/s AZ I United States Patent C) 3,049,133 DISHWASHERJames W. Jacobs, Dayton, Ohio, assignor to General Motors Corporation,Detroit, Mich, a corporation of Delaware Filed Aug. 31, 1959, Ser. No.837,159 3 Claims. (Cl. 134-57) This invention relates to a domesticappliance and more particularly to an improved dishwashing apparatus.

In certain areas of the country the water supplied to dishwashingapparatus contains minerals and other foreign matter. Thischaracteristic of the washing fluid creates undesirable spotting of thedishes after they are dried. Efforts in the past have been directed tothe use of additives in the water which help in shedding the waterdroplets from the surfaces of just washed dishes-a procedure known assheeting off. Washing agents called surfactants or wetting agents havebeen added to the final rinse water and thereby distributed over thesurfaces of the dishes being rinsed to aid in the sheeting-off process.This invention teaches a dishwashing apparatus which may be operated ina manner to eliminate the need for such surfactants or which, if usedwith surfactants, will produce an simproved dishwashington result-dishesand and glassware free of troublesome water spotting.

Accordingly, it is an object of this invention to position a heaterelement in a dishwashing apparatus in a manner to aid in boostingtemperatures of the washing fluid and to vaporize a portion of the rinsefluid in steam bathing the utensils after being washed.

A further object of this invention is the provision of a sump having aheater installed therein for distilling ofi vapor which may be utilizedto remove foreign matter or spot producing materials from the surfacesof the dishes being washed.

A further advantage of this invention as it relates to the last citedobject lies in the fact that 'a heater in the sump arrangement permitsthe distillates and the removed spot producing materials to remain insolution during the steam bathing process, thereby eliminating the buildup of solids on components of the dishwasher.

A more specific object of this invention is the provision for a heaterin a dishwasher, wherein said heater is arranged to be submerged duringcertain portions of the dishwashing cycle for heating water andgenerating steam and exposed during other portions of the cycle forheating air to aid in drying dishes.

It is also an object of this invention to provide a nonprecipitatingwater softener in the rinse water of a dishwasher to aid in theprevention of dish spotting.

A more specific object of this invention is the provision for dispensingan alkali-metal metaphosphate during the fill period preceding eachrinse period.

Another object of this invention is the provision of dispensers for anon-precipitating water softening agent and a surfactant or wettingagent to aid in the prevention of spotting from dishwashing.

It is also an object of this invention to hold in abeyance thedishwashing cycle before the final rinse until the water for rinsingreaches a predetermined temperature suitable for sanitizing orsterilizing the dishes being washed.

Still another object of this invention is the provision for placing awasher timer motor in series with a water temperature responsive switchactuatable only just preceeding he final rinse of a wash cycle.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings where- "ice in preferred embodiments of the present inventionare clearly shown.

In the drawings:

FIGURE 1 is a generally schematic side view of a dishwasher suitable foruse with this invention;

FIGURE 2 is a schematic wiring diagram for operating the dishwasher ofFIGURE 1 in accordance with the concepts of this invention; and

FIGURE 3 is a timer advance or timer cycle chart showing the position ofthe switches illustrated in the wiring diagram of FIGURE 2 throughout adishwashing cycle.

In accordance with this invention and with reference to FIGURE 1, adishwasher 10 is shown comprised of a casing 12 enclosing a dishwashingchamber 14. The casing 12 has a horizontal bulkhead portion 16 whichdefines a generally conical sump 18 in a central portion thereof-theentire bulkhead 16 forming the, bottom wall of the dishwashingcompartment 14. At the front of the dishwasher 10, the casing 12 isformed with an opening 20 which is selectively closed by a horizontallypivoted door 22. Within the door certain control components may beincluded such as a timer 24, a detergent dispenser 26 and anon-precipitating water softener dispenser 28 for use during the rinseof the dishwashing cycle. The dispenser 28 may be of the type having areserve capacity of water softener and mechanism for dispensing measuredquantities of the softener each time the dispenser is actuated.

The water distribution system of the dishwasher 10 may include a pump 30driven by the motor 32. A spray tube 34 is disposed within a centralportion of the dishwashing chamber 14 and adapted to be rotatablymounted at the rear wall of the casing 12. Connecting the outlet 36 ofthe pump 30 and the inlet to the spray tube 34 is a conduit 38. Anormally closed drain or diverter valve 40 is interposed between thepump and the spray tube and is connected also to a drain line 42 so thatthe out-put of the pump may be selectively directed either to the spraytube 34 or to a remote drain. Thus, it may be seen that the operation ofthe pump 30 by the energization of motor 32 will withdraw fluid from thedishwashing sump 18 and supply this fluid to the spray tube 34, fromwhich point it will be distributed in a thorough fashion throughout thedishwashing chamber 14. Any suitable filter 43 is positioned in the sumpto strain sediment from the circulating water. Support racks 44 aredisposed within the dishwashing chamber 14 on opposite sides of thespray tube 34. Such support rack-s may be used to retain dishes such as46 or other utensils commonly used domestically. It will be noted thatthe dishes are disposed in a manner to receive the forceful jets of thespray tube 34 on the sides generally soiled.

Washing fluid must *be supplied to the chamber 14 and for this purpose,a' supply valve 48 is connected to a domestic water supply line 50.Water is supplied through an outlet 52 to the dishwashing chamber 14 andflows by gravity to the sump 18 which overlies the inlet to the pump 30.Fluid for washing and fluid for rinsing is supplied to the sump 18through the water inlet 52. Further, the timer 24 is utilized toselectively control the electrical components of the dishwasher ineither a washing operation or a rinsing operation as will be more fullydescribed hereinafter.

Within the sump 18 is located a tubular heater 54 which may have anysuitable configuration. The heater 54 is retained below the upper levelof the sump 18 so that it may be inundated or submerged in the sumpwater when the sump is substantially full. Note, however,that the heater54 is retained in an upper portion of the sump so that it will besuspended in relatively clean water, i.e. water from which the heavysediment has settled. During a dishwashing cycle, the heater 54 isutilized selectively to maintain the temperatureof the water in the sump18 at a desired level during the washing and rinsing operations, but toelevate the temperature of the water sub sequent to the final rinsingoperation to vaporize a certain portion of the rinse water from the sump18 in a manner to be described more fully hereinafter. For this purpose,the heater 54 should have a wattage in the neighborhood of 8004200watts.

In this invention there is provided a dishwashing cycle having aplurality of rinsing periods. It is a part of this invention to withholdor delay the final rinsing operation until the temperature of the rinsewater has reached a temperature suitable for sanitizing or sterilizingthe dishes. Thus, the sump 18 includes a temperature responsive deviceor thermostat 56 in asidewall thereof to sense the temperature of waterwithin the sump.

Referring now to FIGURE 2, a control circuit is set forth embodying in arepresentative fashion the major control concepts of this invention. Thecircuit includes a domestic household electrical supply indicated by L1and L2. The circuitry further includes a solenoid 58 for actuating thenormally closed drain valve 40, a solenoid 60 for actuating thedetergent dispenser 26, a solenoid 62 for actuating thenon-precipitating water softener dispenser 28, a solenoid 64 foractuating the water supply valve 48, and the heater 54. These variouscomponents and their respective circuits are actuated by a plurality oftimer switches which are cam actuated by a timer shaft 66 driven by atimer motor 68. More specifically, a cam actuated switch 72 is arrangedin the drain valve circuit and adapted to close the circuit with a timercontact 1; a cam actuated switch 74 in the circuit for the pump motor 32and adapted to close the circuit with a timer contact 2; a cam actuatedswitch 76 in the detergent dispenser circuit and adapted to close thecircuit with a timer contact 3; a cam actuated switch 78 in thenon-precipitating water softener dispenser circuit and adapted to closethe circuit with a timer contact 4; a

cam actuated switch 80 in the fill valve circuit and adapted to closethe circuit with a timer contact 5; and a cam actuated switch 82 in theheater circuit and adapted to close a direct circuit to the heater on atimer contact 6.

A main line cam actuated switch 84 operates on a timer contact 8 in thecircuit to the timer motor 68 and, thus, is adaptedto interrupt thetimed cycle whenever opened by the selective manual positioning orautomatic rotation of the cam actuating shaft 66. More particularly, acontrol knob (not shown) is connected to the shaft 66 and is adapted tobe pushed or pulled to close or open the circuit for a dishwashingcycle. As the shaft is rotated to a position wherein the timer contact 8is closed, the timer motor 68 will be energized to commence thedishwashing cycle. Further'when the contact 8 is opened by thesequential positioning of the cam actuated switch 84, the dishwashingcycle is terminated.

As a safety precaution, the circuitry includes the switch 70 whichoperates in a safety fashion to condition the circuit for energizationwhenever the door 22 to the dishwashing chamber 14' is closed. The onlycomponent of the dishwasher which is not subject to the closure of thedishwashing access door 22 is the drain valve 58. The desideratum ofthis, in case of machine malfimction, is simply to have the dishwashingcompartment drained rather than to retain the water therein until themalfunction is corrected. The normally open drain valve 40 efiects thisaim. This circuitry also prevents a draining of the sump 18 when thedoor 22 is opened to add a dish during a portion of the dishwashingcycle where switch 72 is closed. v v I One concept of this inventioninvolves the final rinse period in the dishwashing cycle. Moreparticularly, it is desirable to have a predetermined water temperaturesufiiciently high to sanitize or sterilize the dishes prior toinitiating the final rinse. For this purpose, a by-pa's's circuit isincluded in the heater circuit. This parallel circuit terminates in acontact 7 selectively closed by the timer switch 82. Further, thecircuit includes a relay solenoid 88 which actuates a switch 90 in thecircuit for the timer motor 68. The other terminus of the circuit 92connects to the heater circuit and thus places the solenoid 88 in serieswith the heater 54 and the timer contact 7. Between the solenoid 88 andthe Contact 7 is a temperature responsive switch 94 which is normallyclosed when the sump water temperature is below F. The switch 94 isactuated by a bimetal 96 in the thermostat or temperature responsivedevice 56. In this fashion, the circuit to the solenoid 88 is maintainedin an open condition by the bimetal 96 above 150 F. to prevent theswitch 90 from interrupting the operation of the timer motor 68. Duringoperation the timer cycle is adapted to maintain the timer switch 82 oncontact 7 only during the fill and the delay period just preceding thefinal rinse. This delay, as indicated representatively in FIGURE 3, isof indefinite duration depending on the length of time which it takesthe heater 54 to increase the temperature of the washing fluid in thesump 18 to the desired value; Once the desired temperature is reached,switch 24 will open to deenergize solenoid 88, switch 90 will close andthe timer motor 68 will be energized to advance the cam actuatedswitches into the final rinse cycle with the pump motor 32 energized forwater distribution.

The operation of the dishwashing apparatus of this invention will not bedescribed with reference to the timer cycle chart in FIGURE 3. The solidblocks in the chart indicate a closed contact while the open blocksindicate an open contact. The dishwashing cycle is initiated when anoperator manually rotates the timer shaft 66 to close the line switch 84to energize the timer motor 68. At this point, the drain valve isenergized to open the drain 40 and permit a flushing operation whichwastes the cool water standing in the house supply lines until thetemperatures thereof have advanced to a satisfactory wash level. At thesame time, the pump motor 32 is energized with contact 2 being closed bytimer switch 74. This serves to pump the waste fluid to a remote drainwhere gravity flow is not possible. To flush the washing chamber 14, ofcourse, the fill valve 48 must be energized, the timer switch 80 beingclosed on contact 5 for this purpose. At the termination ofa briefflushing period, the drain valve solenoid 58 is deenergized and thewater entering through the inlet 52 is retained in the sump -18. At thistime, timer switch 76 closes on contact 3 to actuate the detergentdispenser 60 and admit the detergent from the dispenser 26 into thewashing chamber 14. Next, the wash period is initiated wherein the pump30 is continuously operated to recircuate the water plus the detergentfrom the sump 18 to the spray tube 34. This washing portion of thedishwashing cycle may extend over a period of time suflicient to assureclean dishes and utensils, in this instance five timed increments orapproximately five minutes being deemed a suflicient period. After thewash period, the drain valve is energized to permit the pump 30 to forcethe soiled wash water to drain. Next, following the second fill, is thefirst rinse period wherein the soiled wash fluid is rinsed from thesurface of the dishes. A second rinse period has also been provided inthis improved cycle and operates substantially the same as the first.

It should be noted that contact 4 is closed by timer switch 78 duringeach of the rinse fills, thereby to place a quantity of anon-precipitating water softener into Dispenser 28 automaticallydispenses an alkali metaphosphate material such as sodium metaphosphate,potassium'metaphosphate, lithium metaphosphate or ammonium metaphosphateto eliminate evidence of mineral deposits from the dishes or glasswarefollowing the drying cycle. In addition, a third dispenser (not shownbut substantially the same as the metaphosphate dispenser 28) may beutilized for a surfactant, such as Triton CF-lO (Rohm and Haas Company)mixed with isopropanol and water, to elfectively wet the surfaces of thedishes as an aid in the sheeting-off water droplets. The alkali-metalmetaphosphates eifectively soften the water against soaps withoutprecipitates of calcium and magnesium which exist as soluble salts inmost waters.

Subsequent to the final rinse, the timer switch 32 is sequentiallypositioned by the rotation of timer shaft 66 from the contact 6 to thecontact 7, thereby placing the rinse water temperature responsivecircuit in series with the heater 54. The timer switch 82 is athree-position switch having a neutral position interposed between thetimer contacts 6 and 7. If, at this time, the water temperature withinthe sump 18 is below 150 F, the switch 94 will be closed and thesolenoid 88 and heater 54 thus energized. With this energiz-ation, theswitch 96 in the timer motor circuit will be opened and the advance ofthe dishwashing cycle will be interrupted until the then energizedheater 54 elevates the temperature of the Water within the sump. Thethermostat 56 including the bimetallic element 96 is located within thewall of the sump 18 and thus senses the rising temperature of the watertherein and is adapted to open the switch 94 when the desiredtemperature is reached. At this time the parallel n'nse watertemperature responsive circuit will be deenergized and the timer motorswitch 9% closed to again energize the timer motor and cause thecontinuation of the dishwashing cycle.

At the initiation of the final rinse period or when the temperature ofwater within the sump 18 reaches 150 F., the timer switch 82 will bemoved to its neutral position, the pump motor 32 will be energized withthe closing of contact 2 and the timer motor 68 will be energized tocontinue the dishwashing cycle. The pump will act to circulate rinsewater throughout the dishwashing chamber and over the dishes therein.The final rinse water may include the metaphosphate and the surfactant,mentioned immediately hereinabove.

At the conclusion of the third rinse cycle, it should be noted that thedrain valve is not energized. It is at this point that the major conceptof this invention is practiced, i.e. the heater 54 is energized for anextended period while submerged in the rinse water remaining in the sumpfrom the final rinse. As the temperature of the fluid in the sump iselevated, a portion thereof will be boiled-off or vaporized from thesump water. Dense clouds of steam will surround and coat the dishes andutensils therein with large amounts of distilled condensate which willsheet-off or flood the spot producing minerals or materials from thesurfaces of the dishes being washed. As aforesaid, the heater 54 isretained within a top portion of the sump so that the vaporizing processis more easily accomplished without an excessively large heater and in amanner to permit the heavy sediment to fall to the bottom of the sump,thereby eliminating the possibility of its being redistributed to thesurfaces of the dishes. The disposition of the heater just beneath thetop surface 100 of the sump water takes advantage of thermalStratification of the water to expedite the steam vaporization. A totalof five timed increments or approximaely five minutes has been utilizedin this invention for the vapor or steam bath. However, it is within thepurview of this invention to utilize a time interval sufliciently longto sheet-off satisfactorily Whatever mineral content or spot producingdroplet residue might result from an areas particular water problem. Inareas where the water is harder than others, it will be necessary toprovide a longer steam bathing operation and vice versa.

With the steam generating arrangement of this invention wherein theheater 54 resides within the sump 18, it should be noted that a largeamount of washing or rinsing solution remains in the sump 18 at alltimes. This solution becomes more concentrated with the water hardnessmaterials as the steam is generated by the dis tillation of sump water.But, nevertheless, these materials which cause water spotting areretained in solution so that they may be pumped to drain at theconclusion of the steam bathing operation. This eliminates thepossibility of the hardness materials precipitating out and becomingcorroded onto the surfaces of the dishwasher. Here, again, it isimportant to note that the heater 54 lies within an upper portion of thesump 18 and just below the surface of the fluid laying within the sump18.

It should be recognized that the amount of steam vaporized from the sump18 during the steam bathing operation depends on two variables, i.e. thesize of the heater 54 and the length of time during which the heat isenergized. Either one of these variables may be altered to vary theamount of steam generated during the bathing process. For instance, theheater 54 may be increased in wattage to more vigorously boil the Waterin the sump or a small heater 54 may be energized for a longer period oftime. In either case, it is important merely to recognize that theresult of the steam bathing or condensate flooding operation will dependon suflicient distilled condensate being deposited over and around thedishes washed to remove any of the mineral or water hardness depositsfrom the surfaces of the dishes. This steam bathing operation as seen inthe timer cycle chart of FIGURE 3 has the heater 54 energizedcontinuously during this steam bathing portion of the dishwashing cycle.At the conclusion thereof, the drain valve solenoid 58 and the pumpmotor 32 are ener gized to remove the concentrated solution of rinsewater and spot producing materials to drain.

Following the steam bathing operation, the dishwashing cycle concludeswith a period of drying during which the heater 54 is energized to drythe dishes in the support racks 44. After a predetermined interval, inthis case seven timed increments or approximately seven minutes, the camactuated line switch 84 will be opened as the last act in the timedcycle, the timer motor 68 will be deenergized and the dishwashing cyclewill be terminated.

Although the foregoing cycle included three rinses, it should berecognized that more or less rinses is immaterial in so far as thepractice of this invention is concerned. It must be borne in mind merelythat the final rinse water is retained in the sump so that the heaterwhich is inundated thereby may be energized to vaporize a sufiicientquantity of steam to thoroughly coat and cover the dishes and glasswarewith distilled condensate in removing the spot producing materialtherefrom. Then, too, the foregoing cycle included the addition of ametaphosphate material to the rinse Water and/or a wetting agent to helpthe sheeting-01f of the condensate from the dishes. Although either orboth of these additions further improve the end result, they are notessential to the instant teaching relating to steam bathing. The steambathing operation with an inundated or submerged heater is ettective initself to minimize water spots and the addition of a non-precipitatingwater softener and a surfactant merely acts as an adjunct in the overallprocess.

It should now be seen that an improved dishwashing cycle has been setforth wherein superior results are assured. A heater, controlled inaccordance with the circuitry of this invention, is energized as abooster during the wash period of the operating cycle and during thefirst and second rinses. In this way, the water temperatures aremaintained during the extended period of Water recirculation by the pump30. As an additional feature of this invention the final rinse isprovided with a control circuitry which includes a temperatureresponsive device to interrupt the timer motor and thus the theoperation of perature sensing means immediately preceding said rinseadvance of the dishwashing cycle until the temperature of the waterrinthe sump 18 has reached a predetermined temperature deemed satisfactoryfor sanitizing and sterilizing purposes. Finally, the improved cycleincludes an arrangement whereby large quantities of steam are vaporizedby a heater disposed just below the surface of rinsing fluid within thedishwasher sump. As the sump water is distilled, the vapor rises,surrounds the dishes being washed and condenses thereon to sheet off orflood the. surfaces thereof, thereby removing the spotproducing-materials which reside on the dishware subsequent to thepreceding washing and rinsing cycles. This sheeting-ofr' will carrythese materials to the sump 18 by gravity, the solution therein becomingmore concentrated as the condensate cleanses the dishes. However, theheavier sediment and mineral desposits will fall to the bottom of thesump and thus be relatively removed from the action of the heater 54 inthe upper part of the sump fluid. This arrangement prevents the sumpfrom being boiled dry and thus retains the minerals or foreign matter insolution for easy removal from the sump at the end of the dishwashingcycle.

While the embodiments of the present invention as herein disclosed,constitute preferred forms, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1.- A dishwasher comprising, a casing defining a washing chamber havinga sump and an access opening, said sump adapted to retain a fluid havingforeign matter therein, a heater in an upper portion of said sump andadapted to be inundated by said fluid, a fill valve in fluid supplyrelationship to said chamber and said sump, means for sensing thetemperature of said fluid, a Washing agent dispenser for said chamber, arinsing agent dispenser for said chamber, a drain valve for said sump,means for supporting dishes and the like in said chamber, means remotefrom said sump for distributing said fluid from said sump over saiddishes and the like, power means for said distributing means, a controlcircuit for said dishwasher including means for energizing anddeenergizing said heater, said fill valve, said temperature sensingmeans, said washing agent dispenser, said rinsing agent dispenser, saiddrain valve, and said power means, and a timer for sequentiallyactuating said energizing and deenergizing means in a dishwashing cycleincluding periods of fill, wash, rinse, and dry, said energizing "anddeenergizing means being actuated to energize said fill valve duringsaid fill periods, said washing agent dispenser during said wash period,said rinsing agent dispenser during said rinse period, said drain valveafter said wash period and said rinse period, and said heater duringsaid dry period after said sump has been drained,

said timer being responsive to said temperiod, and said energizing anddeenergizing means being further actuated by said timer before said dryperiod and before said drain valve is energized after said rinse; periodto energize said heater for a suflicient time interval to generate aquantity of vapor to bathe said foreign: matter from said dishes or thelike.

2. In combination in a washing apparatus, a casing defining a washingchamber and a fluid receptacle at the bottom of said chamber, means forsupporting utensils to be Washed in said chamber, means for supplying awash fluid and a rinse fluid to said receptacle, means for distributingsaid fluids in said chamber in periods of wash and rinse, heating meansin said receptacle below the surface of said fluids supplied, means forretaining the rinse fluid in said receptacle after said rinse period,and timer means for controlling said distributing means, said retainingmeans and said heating means, whereby after said rinse period saiddistributing means is deenergized and said heating means is energized tovaporize a portion of said retained rinse fluid to bathe said utensilsextensively with the distilled condensate from said vaporized rinsefluid.

3. In combination. with a washer of dishes or the like having a casingdefining a washing compartment, a sump in said compartment for retaininga fluid having foreign matter therein, a fluid valve for filling saidsump, a heater in an upper portion of said sump and means for supportingsaid dishes or the like in said compartment, a control circuitcomprising, means for actuating said valve to fill said sumpsequentially with a Wash fluid and a rinse fluid and submerge saidheater in said rinse fluid, means for actuating said heater, and timermeans for selectivelyv controlling both of said actuating means to causesaid heater to change a portion of said rinse fluid into steam, saidsteam thereby generated con densing on said dishes or the like insuflicient quantity to bathe said foreign matter from said dishes or the.like, densed steam returns to said sump after said bathing.

References Cited in the file of this patent UNITED STATES PATENTS1,687,458 Lancelot et a1. Oct. 9, 1928 2,216,388 Hampel Oct. 1, 19402,217,705 Rataiczak et a1. Oct. 15, 1940 2,664,094 Spragins Dec. 29,1953 2,671,037 Stoddard Mar. 2, 1954 2,701,574 Hollerith Feb. 8, 19552,760,502 Rumbaugh Aug. 28, 1956 2,781,765 Steidley Feb. 19, 1957FOREIGN PATENTS 859,597 Germany Dec. 15, 1952 whereby saidvforeignmatter contaminated con-

